This dissertation investigated the relationships between age, stroke rate (SR), stroke length (SL), active drag, and oxygen uptake in freestyle (front crawl) swimming. Part 1 looked at the effects o f systematic changes in SL at a given velocity on active drag and oxygen uptake in a group of collegiate varsity swimmers (both men and women). Part 2 looked at the effects of age on the SL-SR relationship in a large sample of masters swimmers swimming the 100 freestyle at two different national championships. The results of part 1 showed that both men and women had a significant positive quadratic relationship between active drag and stroke length (i.e., active drag was minimized at a specific SL value and increased with shorter and longer strokes). A correlation was found between active drag and oxygen uptake, but oxygen uptake did not show a significant quadratic relationship of its own with SL. The results of part 2 showed that decreases in speed with age resulted from declines in both SL and SR but that SR was the dominant factor in speed declines for both men and women. The take-home message from this dissertation is that swimmers need to pay attention to the causes of the decline in swimming speed with age. Younger individuals need to make sure they are training properly to optimize their SL-SR relationship to minimize drag and possibly oxygen uptake. Maintaining a proper balance between SR and SL may help reduce the rate of decline in swimming as swimmers age. Whereas skilled swimmers tend to demonstrate longer SL than unskilled swimmers, drills for increasing SR (e.g., tempo training) should also be emphasized as swimmers get older because SR was found to be the dominant cause of speed decrease with age, at least in the 100 freestyle events.